The present invention concerns a catalyst containing a sulfide phase comprising (a) sulfur (b) and at least one element A selected from the group consisting of group IIIB, including the lanthanides and actinides, group IVB and group VB and optionally (c) at least one element B selected from the group consisting of group VIIB and group VIII and a mixture therof, said sulfur being present in a quantity higher than the quantity corresponding to 40% of the stoichiometric quantity of sulfur in the sulfide compounds of elements from groups IIIB, IVB, VB, VIIB and VIII and optinally at least one porous amorphous or low crystallinity type matrix.
More particularly, the present invention relates to a catalyst containing a multimetallic sulphide phase comprising sulphur and at least one element A selected from the group consisting of elements from group IIIB, including the lanthanides and actinides (group 3 in the new notation for the periodic table: xe2x80x9cHandbook of Chemistry and Physicsxe2x80x9d, 76th edition, 1995-1996, inside front cover), and group IVB (group 4), at least one element B selected from the group consisting of elements from group VIIB (7) and group VIII (groups 8, 9 and 10 in the new notation for the periodic table), said mixed sulphide phase optionally being associated with a porous matrix, generally an amorphous or low crystallinity oxide type matrix, optionally at least one element selected from elements from group VB (5), group VIB (6), optionally at least one element selected from the group formed by P, B and Si, and optionally at least one source of anions from group VIIA (group 17).
The present invention also relates to a supported sulphur-containing catalyst for hydrorefining or hydroconversion, containing at least one sulphide of at least one element selected from group IIIB, including the lanthanides and actinides, group IVB, group VB (groups 3, 4, 5 in the new notation for the periodic table: xe2x80x9cHandbook of Chemistry and Physicsxe2x80x9d, 76th edition, 1995-1996, inside front cover), associated with at least one porous matrix, generally an amorphous or low crystallinity oxide type matrix. The catalyst can also optionally contain at least one zeolitic or non zeolitic molecular sieve and optionally at least one element from group VIII (groups 8, 9, 10 in the new notation for the periodic table), optionally at least one element selected from the group formed by P, B, Si, and optionally at least one element from group VIIA (group 17). The catalyst comprises a quantity of sulphur such that the degree of sulphurisation is over 40%.
The present invention also relates to the use of the simple sulphides and the mixed sulphides obtained as catalysts for hydrorefining and hydrocracking, for example for hydrogenation, hydrodenitrogenation, hydrodeoxygenation, hydrodearomatization, hydrodesulphurization and hydrodemetallization of hydrocarbon-containing feeds containing at least one aromatic and/or olefinic and/or naphthenic and/or paraffinic type compound, said feeds possibly containing metals and/or nitrogen and/or oxygen and/or sulphur.
Sulphide compounds, and in particular sulphides of transition metals, can be used as catalysts for carrying out hydrotreatment reactions in petroleum refining and in petrochemistry.
Sulphides of transition metals and rare earths (lanthanides) are also used in lubricants, pigments, battery electrodes, materials for sulphur detectors, materials with specific optical properties, additives for luminescent materials, and anti-corrosion coatings in sulphur-containing atmospheres.
In general, the properties of simple sulphides are often improved by the addition of a second element leading to the formation of an intimate association of two elements in the sulphide phase, hereinafter termed a mixed sulphide. As an example, the addition of nickel to molybdenum sulphide substantially improves the catalytic activity of tungsten sulphide for hydrogenation of aromatic compounds (Ahuja, S. P., Derrien, M. L., Le Page, J. F., Industrial Engineering Chemistry Products Research Development, volume 9, pages 272 to 281, 1970). Adding cobalt to molybdenum sulphide substantially improves the activity of the molybdenum sulphide for hydrodesulphurisation of petroleum cuts.
The simple sulphides and the mixed sulphides can be synthesised by a number of methods which are well known to the skilled person.
Crystallised transition metal or rare earth simple or mixed sulphides can be synthesized by reacting transition metal or rare earth type elements with elemental sulphur at high temperature in a process which is well known to the skilled person in the solid state chemistry field but is expensive, in particular as regards industrial application.
The synthesis of simple sulphides and the one of bulk or supported mixed sulphides by reacting a suitable precursor in the form of a mixed oxide of transition metals and/or rare earths impregnated with a sulphur compound in the liquid phase followed by treatment in hydrogen in a traversed bed reactor is well known to the skilled person.
The synthesis of bulk sulphide catalysts or sulphide catalysts supported on a porous matrix by treatment of a bulk oxide precursor or an oxide precursor supported on a porous matrix in hydrogen with a sulphur-containing hydrocarbon feed, in particular sulphur-containing petroleum cuts such as gasoline, kerosene or gas oil, to which a sulphur compound, for example dimethyldisulphide, can optionally be added, is also well known to the skilled person.
Bulk sulphides can also be synthesised by co-precipitation, in a basic medium, of sulphur-containing complexes in solution containing two cations. This method can be carried out at a controlled pH and is termed homogeneous sulphide precipitation. It has been used to prepare a mixed sulphide of cobalt and molybdenum (G. Hagenbach, P. Courty, B. Delmon, Journal of Catalysis, volume 31, page 264, 1973).
Synthesizing bulk sulphide catalysts or sulphide catalysts supported on a porous matrix by treatment of a bulk oxide precursor or an oxide precursor supported on a porous matrix in a hydrogen/hydrogen sulphide mixture or nitrogen/hydrogen sulphide mixture is also well known to the skilled person.
U.S. Pat. No. 4,491,639 describes the preparation of a sulphur-containing compound by reacting elemental sulphur with V, Mo and W salts and in particular V, Mo and W sulphides optionally containing at least one of elements from the series C, Si, B, Ce, Th, Nb, Zr, Ta and U in combination with Co or Ni.
Other methods have been proposed for the synthesis of simple sulphides. As an example, the synthesis of crystallized simple sulphides of rare earths described in U.S. Pat. No. 3,748,095 and French patent FR-A-2 100 551 proceeds by reacting hydrogen sulphide or carbon disulphide with an amorphous rare earth oxide or oxycarbonate at a temperature of over 1000xc2x0 C.
European patents EP-A-0 440 516 and U.S. Pat. No. 5,279,801 describe a process for synthesizing simple transition metal or rare earth sulphur-containing compounds by reacting a transition metal or rare earth compound with a carbon-containing sulphur compound in the gaseous state, in a closed vessel at a moderate temperature of 350xc2x0 C. to 600xc2x0 C.
However, it is well known that certain elements such as group IIIB elements, including the lanthanides and actinides, group IVB elements, and group VB elements, are very difficult to sulphurise. It is also well known that elements from groups IIIB and IVB, in a bulk or supported oxide form, are very difficult to sulphurise in the form of mixed sulphides. The known sulphurisation methods which are routinely used industrially and in the laboratory, such as sulphurisation in a gaseous hydrogen/hydrogen sulphide mixture or liquid phase sulphurisation using a mixture of a hydrocarbon feed and added dimethyldisulphide, are ineffective when sulphurising such solids.
The considerable amount of research carried out by the Applicant on preparing sulphide catalysts based on sulphides of elements from groups IIIB, including the lanthanides and actinides, and group IVB, and numerous other elements of the periodic table, mixed with at least one element selected from group VIIB and group VIII elements, in bulk or associated with a matrix, have led to the discovery that, surprisingly, by reacting a compound of sulphur and carbon containing no hydrogen, such as carbon disulphide CS2, carbon oxysulphide COS, or carbon sulphide CS, with a powder containing at least one element selected from group IIIB, including the lanthanides and actinides, group IVB and at least one element selected from elements from group VB, group VIB, group VIIB and group VIII, in a closed vessel, produces a multimetallic sulphide type compound which may be properly crystalline. Without wishing to be bound by any particular theory, it appears that sulphurisation is produced by decomposition of the carbon sulphide followed by reaction thereof with the compounds of the elements present in the powder forming, from the precursor surface, a sulphide compound which intimately associates the cations, until the precursors are exhausted. Thus the catalysts of the invention contain a quantity of sulphur such that the degree of sulphurisation is over 40%, preferably over 50% and more preferably over 60%.
The term xe2x80x9cdegree of sulphurisationxe2x80x9d as used in the present discussion means the quantity of sulphur fixed on the catalyst with respect to the stoichiometric quantity of sulphur in the metallic sulphide compounds.
Other research studies carried out by the Applicant on preparing sulphide catalysts based on sulphides of elements from groups IIIB, IVB, VB and numerous other elements of the periodic table, used alone or as mixtures, associated with a matrix, have led to the discovery that, surprisingly, by simultaneously reacting elemental sulphur and carbon with a powder containing at least one element selected from group IIIB, including the lanthanides and actinides, group IVB, group VB, and possibly at least one element from group VIII, in a closed or open vessel in an autogenous or inert atmosphere, produces an amorphous or crystalline sulphide compound with a degree of sulphurisation of over 40%. Without wishing to be bound by any particular theory, it appears that sulphurisation is obtained by reducing a precursor compound containing the element or elements selected from group IIIB, including the lanthanides and actinides, group IVB, group VB, and optionally at least one group VIII element, with carbon with simultaneous sulphurisation of the reduced element by the sulphur until the precursor containing the element or elements selected from group IIIB, including the lanthanides and actinides, group IVB, group VB, and optionally at least one group VIII element, is exhausted.
As stated above and according to a first preferred embodiment of the invention, one of the preferred catalyst of the invention contains a multimetallic mixed sulphide phase comprising (a) sulphur (b) and at least one element A selected from the group consisting of elements from group IIIB, including the lanthanides and actinides, group IVB and mixtures thereof and (c) at least one element B selected from the group consisting of elements from group VIIB, group VIII and mixtures thereof, said sulfur being present in a quantity higher than the quantity corresponding to 40% of the stoichiometric quantity of sulfur in multimetallic sulfide compounds of elements from groups IIIB, IVB, VIIB and VIII.
The group IVB elements are selected from titanium, zirconium and hafnium, preferably titanium. The group IIIB elements are selected from yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thullium, ytterbium, lutetium, actinium, thorium and uranium.
The group VIII elements are selected from nickel, iron, ruthenium, osmium, rhodium, iridium, platinum, palladium and cobalt, preferably cobalt, nickel or iron.
The group VIIB elements are selected from manganese, rhenium and technetium.
The group VIB and VB elements which are optional in this type of preferred catalytic composition are selected from molybdenum, chromium, tungsten, niobium, vanadium and thallium
The bulk mixed sulphide catalyst (multimetallic sulphide catalyst) of the present invention generally comprises at least one metal selected from the following groups and in the following amounts, in % by weight with respect to the total catalyst mass:
0.01% to 40%, preferably 0.01% to 35%, more preferably 0.01% to 30%, of at least one metal selected from elements from groups IIIB and IVB, including the lanthanides and actinides (element A);
0.01% to 30%, preferably 0.01% to 25%, of at least one metals selected from groups VIIB and VIII (element B);
0.001% to 30%, preferably 0.01% to 55%, of sulphur; the catalyst optionally containing:
0 to 30%, preferably 0.01% to 25%, of at least one metal selected from elements from groups VB and VIB;
0 to 20%, preferably 0.1% to 15%, more preferably 0.1% to 10%, of at least one element selected from the group formed by boron, silicon and phosphorous;
0 to 20%, preferably 0.1% to 15%, more preferably 0.1% to 10%, of at least one element selected from group VIIA, preferably chlorine or fluorine.
The supported mixed sulphide catalyst (multimetallic sulphide catalyst) of the present invention generally comprises at least one metal selected from the following groups and in the following amounts, in % by weight with respect to the total catalyst mass:
0.01% to 40%, preferably 0.01% to 35%, more preferably 0.01% to 30%, of at least one metal selected from elements from groups IIIB and IVB, including the lanthanides and actinides (element A);
0.01% to 30%, preferably 0.01% to 25%, of at least one metal selected from groups VIIB and VIII (element B);
0.1% to 99%, preferably 1% to 98%, of at least one support selected from the group formed by amorphous matrices and low crystallinity matrices;
0.001% to 30%, preferably 0.01% to 55%, of sulphur;
the catalyst optionally containing:
0 to 90%, preferably 0.1% to 85%, more preferably 0.1% to 80%, of a zeolite;
0 to 30%, preferably 0.01% to 25%, of at least one metal selected from elements from groups VB and VIB;
0 to 20%, preferably 0.1% to 15%, more preferably 0.1% to 10%, of at least one element selected from the group formed by boron, silicon and phosphorous;
0 to 20%, preferably 0.1% to 15%, more preferably 0.1% to 10%, of at least one element selected from group VIIA, preferably chlorine or fluorine.
The invention also relates to a process for preparing a multimetallic sulphide catalyst, characterized in that at least one compound of sulphur and of carbon containing no hydrogen is used for sulphurisation.
A process for preparing a multimetallic sulphide catalyst of the present invention comprises the following steps:
a) forming a reaction mixture which comprises: a powder or mixture of powders containing at least one element selected from group IIIB, including the lanthanides and actinides, and group IVB, at least one element selected from elements from group VIIB and group VIII, at least one compound of sulphur and of carbon containing no hydrogen, such as carbon disulphide, carbon monosulphide or carbon oxysulphide, preferably carbon disulphide CS2, optionally at least one solid source of carbon, and optionally at least one solid source of sulphur;
b) maintaining the reaction mixture obtained after step a) at a heating temperature of more than 40xc2x0 C. at a pressure of over 0.01 MPa in a reactor.
The reactor may be a closed reactor. In this case, the pressure exerted is the autogenous pressure of the gases produced in carrying out the treatment or it can be the pressure of an inert gas. The reactor can be a traversed bed reactor. In this case, the pressure exerted is that of an inert gas. Preferably, a sealed reactor is used.
The mixture can optionally contain elemental sulphur in its different forms, for example flowers of sulphur or sulphur suspended in an aqueous medium or an organic medium. Sulphur compounds can also be used, such as hydrogen sulphide, sulphur-containing hydrocarbons such as dimethyl sulphide, dimethyl disulphide, mercaptans, thiophene compounds, thiols, polysulphides such as ditertiononylpolysulphide or TPS-37 from ATOCHEM, sulphur-rich petroleum cuts such as gasoline, kerosene, gas oil; however, the presence of a compound containing hydrogen does not in general enable the mixture to be properly sulphurised.
The mixture can optionally contain a carbon source. All of the forms of the carbon source which are known to the skilled person can be used, for example graphite, oil coke, coal coke, amorphous carbon, carbon black, charcoals obtained by partial combustion or by decomposition or by dehydrogenation of vegetable compounds or animal compounds or hydrocarbons. The carbon source generally contains hydrogen and one of its characteristics is its H/C atomic ratio. Preferably, a carbon source with an H/C ratio of less than 2, more preferably an H/C ratio of less than 1.7, and still more preferably an H/C ratio of less than 1.4 is used.
The reaction is carried out under autogenous pressure or under an inert gas. The autogenous pressure is produced by the generation of reaction products such as CO, CO2, H2O, COS and S. The inert gas can comprise at least one of the following compounds: nitrogen, a rare gas such as helium, neon, argon, krypton, xenon or radon, superheated steam or a combination of at least two of these compounds.
The first step of the sulphurisation process of the invention for preparing a multimetallic sulphide catalyst consists of producing a mixture of carbon disulphide and a powder containing one or more compounds comprising at least one element selected from group IIIB, including the lanthanides and actinides, group IVB and at least one element selected from elements from group VIIB, group VIII, optionally solid sulphur, optionally solid carbon, optionally a porous matrix, optionally at least one element from group VB and group VIB, optionally at least one element selected from P, B and Si, and optionally at least one source of group VIIA anions. This first step can be accomplished in several stages.
The second step of the sulphurisation process of the invention for preparing a multimetallic sulphide catalyst consists of reacting the mixture formed in the first step to obtain the sulphurised multimetallic compound. A first method for carrying out the reaction consists of heating the mixture of powders to a temperature in the range 40xc2x0 C. to 1000xc2x0 C., preferably in the range 60xc2x0 C. to 700xc2x0 C., under autogenous pressure. Preferably, a steel autoclave which is resistant to corrosion by sulphur compounds is used. The duration of heating the reaction mixture required for sulphurisation depends on the composition of the reaction mixture and on the reaction temperature.
Also stated above and according to a second preferred embodiment of the invention, another preferred catalyst of the invention contains at least one porous amorphous or low crystallinity type matrix and at least one sulphide of at least one element A selected from the group consisting of elements from group IIIB, including the lanthanides and actinides, group IVB and group VB, the quantity of sulphur fixed on the catalyst being over 40% of the quantity of sulphur corresponding to the stoichiometric quantity of sulphur in the sulphides of elements IIIB, IVB and VB. This preferred catalyst may further comprise at least one metal from group VIII, at least one group VIIA element, at least one zeolite and at least one element selected from the group formed by P, B, Si.
Thus, more particularly, the invention relates to sulphide catalysts comprising at least one group VB metal and at least one group VIII metal, doped with boron and/organic silicon and/or phosphorous.
More particularly again, the invention relates to sulphide catalysts comprising at least one group IIIB metal, including the lanthanides and actinides, and at least one group VIII metal, doped with boron and/or silicon and/or phosphorus.
The group VB elements are selected from vanadium, niobium and thallium; the group IVB elements are selected from titanium, zirconium and hafnium, preferably titanium. The group IIIB elements are selected from yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, actinium, thorium and uranium. The group VIII elements are selected from iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and platinum, preferably iron, cobalt and nickel.
The quantity of sulphur in the catalyst of the invention is such that the degree of sulphurisation is over 40%, preferably over 50% and more preferably over 60%.
This type of catalyst of the present invention generally comprises at least one metal selected from the following groups and in the following amounts, in % by weight with respect to the total catalyst mass:
0.01% to 40%, preferably 0.01% to 35%, more preferably 0.01% to 30%, of at least one metal selected from elements from groups IIIB, IVB and VB (element A);
0.1% to 99%, preferably 1% to 98%, of at least one support selected from the group formed by amorphous matrices and low crystallinity matrices;
0.001% to 30%, preferably 0.01% to 55%, of sulphur;
0 to 30%, preferably 0.01% to 25%, of at least one group VIII metal; and optionally
0 to 90%, preferably 0.1% to 85%, more preferably 0.1% to 80%, of a zeolitic or non zeolitic molecular sieve;
0 to 40%, preferably 0.1% to 30%, more preferably 0.1% to 20%, of at least one element selected from the group formed by boron, silicon and phosphorus;
0 to 20%, preferably 0.1% to 15%, more preferably 0.1% to 10%, of at least one element selected from group VIIA.
The invention also relates to a process for preparing sulphurised catalysts according to the second preferred embodiement, characterized in that the catalyst is sulphurised by a mixture containing at least one source of elemental sulphur and at least one source of carbon in an autogenous and/or inert atmosphere.
More precisely, a process for producing the sulphide catalysts of the present invention comprises the following steps:
a) forming a reaction mixture which comprises: a powder or mixture of powders containing at least one element selected from group IIIB, including the lanthanides and actinides, group IVB and group VB, at least one porous matrix which is generally an amorphous or low crystallinity oxide type matrix, optionally associated with a zeolitic or non zeolitic molecular sieve, optionally at least one group VIII element, optionally at least one source of an element selected from the group formed by P, B and Si, optionally at least one source of anions from group VIIA, at least one source of elemental sulphur and at least one source of carbon, and optionally water;
b) maintaining the reaction mixture obtained after step a) at a heating temperature of more than 40xc2x0 C. at a pressure of over 0.01 MPa in a reactor.
The reactor may be a closed reactor. In this case, it may be charged in the open air and after sealing and reacting, the pressure exerted is the autogenous pressure of the gases produced in the reduction and sulphurisation reactions. The reactor can also be charged in an atmosphere of an inert gas.
The reactor can optionally be a traversed bed reactor, such as a fixed bed, moving bed, ebullated bed, or fluidised bed reactor. In this case the pressure exerted is that of an inert gas.
Preferably, a closed reactor is used.
The sulphur source is elemental sulphur in its different forms, for example flowers of sulphur, sulphur suspended in an aqueous medium or sulphur suspended in an organic medium.
All of the forms of the carbon source which are known to the skilled person can be used, for example graphite, oil coke, coal coke, amorphous carbon, carbon black, charcoals obtained by partial combustion or by decomposition or by dehydrogenation of vegetable compounds or animal compounds or hydrocarbons. The carbon source generally contains hydrogen and one of its characteristics is its H/C atomic ratio. Preferably, a carbon source with an H/C ratio of less than 2, more preferably an H/C ratio of less than 1.7, and still more preferably an H/C ratio of less than 1.4 is used.
The reaction is carried out under autogenous pressure or under an inert gas. The autogenous pressure is produced by the generation of reaction products such as CO, CO2, H2O. The inert gas can comprise at least one of the following compounds: nitrogen, a rare gas such as helium, neon, argon, krypton, xenon or radon, superheated steam or a combination of at least two of these compounds.
The first step of the sulphurisation process for preparing a supported sulphide catalyst according to the second preferred embodiement of the invention consists of producing a mixture of the source of elemental sulphur and the carbon source and a powder containing the compound or compounds comprising at least one element selected from group IIIB, including the lanthanides and actinides, group IVB and group VB, the porous matrix and optionally at least one group VIII element, optionally at least one element selected from P, B and Si, and optionally at least one anion from group VIIA. This first step can be accomplished in several stages.
The second step of the sulphurisation process for preparing a supported sulphide catalyst according to the second preferred embodiement of the invention consists of reacting the mixture formed in the first step to obtain the sulphurised compound. A first method for carrying out the reaction consists of heating the mixture of powders to a temperature in the range 40xc2x0 C. to 1000xc2x0 C., preferably in the range 60xc2x0 C. to 700xc2x0 C., under autogenous pressure. Preferably, a steel autoclave which is resistant to corrosion by the sulphur compounds is used. The duration of heating the reaction mixture required for sulphurisation depends on the composition of the reaction mixture and on the reaction temperature.
Whatever the implemented sulphurization process is and whatever the embodiement of the invention is, compounds containing at least one element selected from group IIIB, including the lanthanides and actinides, group IVB, group VIIB, group VIII, optionally group VB and group VIB, include oxides, hydroxides, oxyhydroxides, acids, polyoxometallates, alkoxides, oxalates, ammonium salts, nitrates, carbonates, hydroxycarbonates, carboxylates, halides, oxyhalides, phosphates, carbamates, thiocarbamates, xanthates, thioxanthates, acetylacetonates, thiometallaates and thiosalts, in particular of ammonium. Preferably, oxides and salts of transition metals, lanthanides and actinides are used.
In each sulphurization process, the preferred phosphorous source is orthophosphoric acid H3PO4, but its salts and esters such as alkaline phosphates and ammonium phosphates are also suitable. Phosphorus can, for example, be introduced in the form of a mixture of phosphoric acid and a basic organic compound containing nitrogen such as ammonia, primary and secondary amines, cyclic amines, compounds of the pyridine family and quinolines and compounds from the pyrrole family.
A number of silicon sources can be used. Thus the following can be used: a hydrogel, an aerogel or a colloidal suspension of an oxide of silicon, precipitation oxides, oxides from the hydrolysis of esters such as ethyl orthosilicate Si(OEt)4, silanes and polysilanes, siloxanes and polysiloxanes. Silicon can be added, for example, by impregnating with ethyl silicate in solution in an alcohol.
The boron source can be a boron salt such as ammonium biborate or pentaborate, or aluminium borate. Boron can, for example, be introduced in the form of a solution of boric acid in an alcohol.
Sources of group VIIA elements which can be used are well known to the skilled person. As an example, fluoride ions can be introduced in the form of hydrofluoric acid or its salts. These salts are formed with alkaline metals, ammonium salts or salts of an organic compound. In the latter case, the salt is advantageously formed in the reaction mixture by reaction between the organic compound and hydrofluoric acid. Hydrolysable compounds which can liberate fluoride ions in water can also be used, such as ammonium fluorosilicate (NH4)2SiF6, silicon tetrafluoride SiF4 or sodium fluorosilicate Na2SiF6. Fluorine can be introduced, for example by impregnating with an aqueous solution of hydrofluoric acid or ammonium fluoride.
The chloride anions can be introduced in the form of hydrochloric acid or its salts. These salts are formed with alkali metals, ammonium or an organic compound. In the latter case, the salt is advantageously formed in the reaction mixture by reaction between the organic compound and hydrochloric acid.
The normally amorphous or low crystallinity porous mineral matrix is generally selected from the group formed by alumina, silica and silica-alumina, or a mixture of at least two of the oxides cited above. Aluminates containing at least two of the metals cited above can also be selected. Preferably, matrices containing alumina are used, in all of its forms which are known to the skilled person, for example gamma alumina.
Mixtures of alumina and silica and mixtures of alumina and boron oxide can also advantageously be used.
In addition to at least one of the compounds cited above, the matrix can also comprise at least one compound selected from the group formed by molecular sieves of the crystalline aluminosilicate type or natural or synthetic zeolites such as Y zeolite, X zeolite, L zeolite, beta zeolite, small pore mordenite, large pore mordenite, omega zeolites, NU-10, TON, ZSM-22, and ZSM-5 zeolite.
The matrix can first be formed and calcined before introduction into the mixture. Forming can be by extrusion, pelletisation, the oil-drop method, rotating plate granulation or any other method which is known to the skilled person. The pre-formed matrix is optionally calcined in air, usually at a temperature of at least 100xc2x0 C., routinely at about 200xc2x0 C. to 1000xc2x0 C.
Each element which may be comprised in the catalyst of the invention and more particularly element from group IIIB, including the lanthanides and actinides, group IVB, group VB, group VIB, group VIIB, group VIII, as well as element selected from the group formed by P, B and Si, and the element selected from group VIIA anions, can be introduced by one or more ion exchange operations carried out on the selected matrix, using a solution containing at least one precursor of a transition metal or rare earth metal.
The matrix can be pre-impregnated with the transition metal salt or rare earth salt, or a salt containing the element selected from P, B and Si or an anion from group VIIA. As an example, impregnation of molybdenum be facilitated by adding phosphoric acid to the solutions, which also enables phosphorous to be introduced to improve the catalytic activity. Other phosphorous compounds can be used, as is well known to the skilled person.
The matrix is preferably impregnated using the xe2x80x9cdryxe2x80x9d impregnating method which is well known to the skilled person.
Impregnation can be carried out in a single step using a solution containing all of the constituent elements of the final catalyst.
When the metal or metals is/are introduced in a plurality of steps for impregnating the corresponding precursor salts, an intermediate step for drying the catalyst must be carried out at a temperature in the range 60xc2x0 C. to 250xc2x0 C.
The mixture of powders containing all or part of the ingredients can be formed, for example by extrusion, pelletisation, the oil drop method, rotating plate granulation or any other method which is well known to the skilled person.
The sulphide catalysts (simple sulphides and multimetallic sulphides) obtained in the present invention are used as catalysts for hydrogenation, hydrodenitrogenation, hydrodeoxygenation, hydrodearomatization, hydrodesulphurization, hydrodemetallization, hydroisomerization and hydrocracking of hydrocarbon-containing feeds containing aromatic and/or olefinic and/or naphthenic and/or paraffinic compounds, said feeds optionally containing metals and/or nitrogen and/or oxygen and/or sulphur. In these applications, the catalysts obtained by the present invention have an improved activity over the prior art.
The feeds used in the hydrotreatment process are gasolines, kerosenes, gas oils, vacuum gas oils, deasphalted or non deasphalted residues, paraffin oils, waxes and paraffins. They may contain heteroatoms such as sulphur, oxygen and nitrogen, and metals. The reaction temperature is in general over 200xc2x0 C. and usually in the range 280xc2x0 C. to 480xc2x0 C. The pressure is over 0.1 MPa and in general over 5 MPa. The hydrogen recycle ratio is a minimum of 80, usually in the range 200 to 4000 liters of hydrogen per liter of feed. The hourly space velocity is generally in the range 0.1 to 20 hxe2x88x921.
The refiner is interested in the hydrodesulphurization activity (HDS), hydrodenitrogenation activity (HDN) activity and the conversion. Fixed objectives have to be achieved under conditions which are compatible with economic reality. Thus the refiner seeks to reduce the temperature, the pressure, and the hydrogen recycle ratio and to maximise the hourly space velocity. The activity is known to be increased by increasing the temperature, but this is often to the detriment of catalyst stability. The stability or service life increases with increased pressure or hydrogen recycle ratio, but this is to the detriment of the economics of the process.
The following examples illustrate the invention without in any way limiting its scope.